Error while trying to connect to RM/CLM with OSLC4J

I am working on Jazz CLM deployment. We are using Jazz CLM 6.0.3 with enterprise type topology and Jazz Authorization Server to manage Authentication, Authorization and SSO.

I should also precise that while all the CLM component (RM, JTS, DM) are behind an reverse-proxy to unify the URL, this is not the case of the JAS server.

I would like to be able to connect to this platform (RM module for example) with some java client build on top of OSLC4J but I am facing a connection issue. The error is not present with a CLM 6.0.2 platform and without usage of Jazz authorization Server. As example, I am able to reproduce it from a simple connection class below: 

import org.apache.http.HttpStatus;

import org.eclipse.lyo.client.oslc.OSLCConstants;

import org.eclipse.lyo.client.oslc.jazz.JazzFormAuthClient;

import org.eclipse.lyo.client.oslc.jazz.JazzRootServicesHelper;

import java.util.logging.Logger;

public class Connexion {

    private static final Logger logger = Logger.getLogger(Connexion.class.getName());

    public void connect() {

        String webContextUrl = "https://clm.server.org/rm";

        String authUrl = "https://clm.server.org/jts";

        String user = "userid";

        String passwd = "passwd";

        String projectArea = "RM PROJ";

        try {

            JazzRootServicesHelper helper = new JazzRootServicesHelper(webContextUrl, OSLCConstants.OSLC_RM_V2);

            JazzFormAuthClient client = helper.initFormClient(user, passwd, authUrl);

            if (client.formLogin() == HttpStatus.SC_OK) {

              String catalogUrl = helper.getCatalogUrl();

            }

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

}

The exception trace that I get when I try to connect is the following:

java.lang.IllegalStateException: Target host must not be null, or set in parameters.

            at org.apache.http.impl.client.DefaultRequestDirector.determineRoute(DefaultRequestDirector.java:706)

            at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:356)

            at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:820)

            at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:754)

            at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:732)

            at org.eclipse.lyo.client.oslc.jazz.JazzFormAuthClient.followRedirects(JazzFormAuthClient.java:204)

            at org.eclipse.lyo.client.oslc.jazz.JazzFormAuthClient.formLogin(JazzFormAuthClient.java:149)

            at com.mathworks.toolbox.oslc_dng.OslcConnection.login(OslcConnection.java:80)

The dependencies used are:

• oslc4j-core-2.1.0.jar
• oslc4j-json4j-provider-2.1.0.jar
• oslc4j-wink-2.1.0.jar
• oslc-query-2.1.0.jar
• oslc4j-jena-provider-2.1.0.jar
• oslc4j-utils-2.1.0.jar
• oslc-java-client-2.1.0.jar
• oslc-trs-2.1.0.jar

Can anybody help me on this topic?